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👑 AUTOIMMUNITY — 1 MINUTE BEFORE EXAM REVISION 🔹📌 Definition 🔹Autoimmunity = immune response against self-antigens causing tissue damage and disturbed function. 🔹🔥 3 THINGS MUST BE PRESENT FOR AUTOIMMUNITY 🔹1. Genetic susceptibility 🔹2. Environmental trigger 🔹3. Loss of self-tolerance 🔹⚠️ Female > Male 🔹⚠️ Usually starts at 20–40 years 🔹⚠️ Chronic and usually irreversible ⸻ 🔹👑 MOST IMPORTANT CAUSES OF LOSS OF SELF-TOLERANCE 🔹1️⃣ Sequestered antigens released 🔹Eye, Brain, Testis, Thyroid, Sperm 🔹2️⃣ Molecular mimicry ⭐⭐⭐ 🔹Microbe resembles self-antigen 🔹🔥 Streptococcus M protein → Rheumatic fever 🔹🔥 Coxsackie B4 → IDDM 🔹🔥 Campylobacter jejuni → Guillain-Barré syndrome 🔹3️⃣ Polyclonal lymphocyte activation 🔹LPS → B-cell activator 🔹Superantigen → T-cell activator 🔹4️⃣ Altered self-proteins 🔹Procainamide → SLE + Autoimmune hemolytic anemia 🔹5️⃣ Abnormal Class II MHC expression ⭐⭐⭐ 🔹Normally only on APCs 🔹IFN-γ causes expression on: 🔹Pancreatic β-cells → IDDM 🔹Thyroid cells → Autoimmune thyroid disease 🔹6️⃣ HLA associations ⭐⭐⭐ 🔹HLA-B27 → Ankylosing spondylitis 🔹HLA-DR2, DR3 → SLE 🔹HLA-DR3, DR4 → IDDM 🔹7️⃣ Cytokine dysregulation / Treg failure 🔹8️⃣ Thymic defects 🔹9️⃣ Hormonal factors 🔹🔟 Complement deficiency ⸻ 🔹👑 AUTOIMMUNE DISEASES & HYPERSENSITIVITY TYPES 🔹🔥 Type II 🔹Autoimmune hemolytic anemia 🔹Graves disease 🔹Myasthenia gravis 🔹ITP 🔹🔥 Type III 🔹SLE 🔹🔥 Type IV 🔹IDDM 🔹Hashimoto thyroiditis 🔹Rheumatoid arthritis 🔹Multiple sclerosis 🔹Guillain-Barré syndrome ⸻ 🔹👑 GRAVES DISEASE ⭐⭐⭐ 🔹Type II hypersensitivity 🔹Stimulating antibody against TSH receptor 🔹Goiter 🔹Exophthalmos (bulging eyes) 🔹Hyperthyroidism ⸻ 🔹👑 MYASTHENIA GRAVIS ⭐⭐⭐ 🔹Type II hypersensitivity 🔹Blocking antibody against ACh receptor 🔹Muscle weakness ⸻ 🔹👑 SLE ⭐⭐⭐⭐⭐ 🔹Type III hypersensitivity 🔹ANA positive 🔹Anti-DNA 🔹Anti-histone 🔹Immune complex deposition 🔹Complement activation 🔹Skin + Kidney + Joints involvement 🔹Female : Male = 10 : 1 ⸻ 🔹🧨 EXAM TRAPS 🔹Molecular mimicry → Rheumatic fever 🔹IFN-γ → Class II MHC expression on non-APCs 🔹Graves = Stimulating antibody 🔹Myasthenia = Blocking antibody 🔹SLE = Type III, not Type II 🔹IDDM = Type IV, not Type II 🔹Females have stronger immune responses due to estrogen 🔹Complement deficiency predisposes to autoimmunity ⸻ 🔹🔪 KILLER MEMORY 🔹**“Mimic → Rheumatic fever, Stimulate → Graves, Block → Myasthenia, Complexes → SLE, T-cells → IDDM.”**

عندي نمونك SLE DR وحدة 3 احرف و الثانية 2 SLE,DR-2,3 اللخ IDDM 4 و ال3 من يمكم

مهم MCQ

بيها ملاحظات اقروها

الي يقرون عالصور هذي مو كاملة اقروا على ذني

Med 5 ثاني صورا سبعا وتسعين ولباقين مالتنا مليار بلميا يتكرر منهم

👑 IMMUNE TOLERANCE —

THE NOTE MOST LIKELY TO APPEAR IN EXAM

🔹 Immune tolerance = Specific unresponsiveness to an antigen despite a normal immune system. ⚡ Central tolerance = Clonal deletion (Negative selection) 🔹Occurs during lymphocyte development. 🔹Self-reactive T cells deleted in thymus. 🔹Self-reactive B cells deleted in bone marrow. 🔹Purpose: prevent autoreactive cells from maturing. ⚡ Peripheral tolerance = Controls self-reactive cells that escape central tolerance 🔹Immunological ignorance. 🔹Anergy (lack of Signal 2). 🔹Treg suppression. 🔹Deletion by Fas-FasL apoptosis. 🔥 Signal 2 = CD28–B7 🔹Signal 1 without Signal 2 → Anergy (functional unresponsiveness). 🔹One of the highest-yield concepts in the lecture. 🔥 Treg cells 🔹CD4⁺ CD25⁺. 🔹Express FOXP3. 🔹Suppress immunity by: 🔹IL-10. 🔹TGF-β. 🔹Prevent autoimmunity. 🔥 *CTLA-4 OR CD152 🔹Inhibitory receptor. 🔹Binds B7. 🔹Turns T cells OFF. 🔹Causes peripheral tolerance/anergy. 🔹 Exam connection 🔹Failure of central or peripheral tolerance → Autoimmune disease. 🔹Killer Memory 🔹Central tolerance deletes the bad cells. 🔹Peripheral tolerance controls the bad cells that escaped. 📕 *CTLA-4 = Cytotoxic T-Lymphocyte Antigen-4 ملاحظة للفهم 🔹CTLA-4 = Cytotoxic T-Lymphocyte Antigen-4 🔹CD designation = CD152 🔹It is an inhibitory receptor on T cells. 🔹Competes with CD28 for binding to B7 (CD80/CD86). 🔹When CTLA-4 binds B7 → T-cell activation is suppressed → tolerance/anergy develops. 🔹🎯 Exam pearl: 🔹CD28 = ON signal 🔹CTLA-4 (CD152) = OFF signal 🔹 Killer memory: 🔹28 activates, 152 terminates. نزلوا شوية جوه ححط الامسكيوات

نمونك بالتعليقات

هاي حسب الاهمية

🔥ULTRA HIGH-YIELD (Almost every immunology exam) B27 → Ankylosing spondylitis DR3 + DR4 → Type 1 DM DR4 → Rheumatoid arthritis DR2 → SLE DR5 → Hashimoto thyroiditis ⸻ 🔹🟡 HIGH-YIELD 🔹DR3 → Celiac disease 🔹DR3 → Graves disease 🔹DR3 → Myasthenia gravis 🔹B27 → Reactive arthritis 🔹B27 → Acute anterior uveitis 🔹DR2 → Multiple sclerosis ⸻ 🔹🌤 MEDIUM-YIELD 🔹DR5 → Pernicious anemia 🔹DR4 → Pemphigus vulgaris 🔹DR2 → Goodpasture syndrome 🔹DR2 → Narcolepsy 🔹Dw3 → Sjögren syndrome ⸻ 🔹⚪ LOW-YIELD / Usually skipped unless mentioned by lecturer 🔹A1 → Graves disease 🔹A1 → Dermatitis herpetiformis 🔹B8 → Autoimmune hepatitis 🔹B8 → Primary sclerosing cholangitis 🔹B13 → Psoriasis 🔹B17 → Psoriasis 🔹DR7 → Steroid-responsive nephrotic syndrome 🔹DR8 → Primary biliary cirrhosis 🔹Dw4 → Rheumatoid arthritis ⸻ 🔹🎯 If I only had 2 minutes before the exam: 🔹B27 → Ankylosing spondylitis 🔹DR3 + DR4 → Type 1 DM 🔹DR4 → Rheumatoid arthritis 🔹DR3 → Celiac disease 🔹DR3 → Graves disease 🔹DR3 → Myasthenia gravis 🔹DR2 → SLE 🔹DR2 → Multiple sclerosis 🔹DR5 → Hashimoto thyroiditis 🔹These alone are probably 90% of what an examiner would actually ask from this table. 👑

الي يريد يحفظها جودة عالية